Isidis Planitia (Mars)

This feature is named after an earlier feature.

Isidis Planitia is a plain located inside a giant impact basin on Mars, centered inside a giant impact basin on Mars, centered. It is the third biggest obvious impact structure on the planet after the Hellas and Argyre basins – it is about 1,500 km in diameter. (wikipedia entry)

A planitia is a low plain. On Mars they are named after the nearest named albedo feature on the Schiaparelli or Antoniadi maps.